Position line

A position line or line of position (LOP) is a line (or, more generally, a curve curve) that can be both identified on a chart (nautical chart or aeronautical chart) and observed on the surface of the earth. The intersection of two position lines is a fix that is used in position fixing to identify the navigator's location.

There are several types of position line:

• Compass bearing – the angle between north and the line passing through the compass and the point of interset
• Transit – a line passing through the observer and to other reference points
• Leading line – the line passing through to marks indicating a safe channel
• Leading lights – the line passing through to beacons indicating a safe channel
• Sector lights – the lines created by masked coloured lights that indicate a safe channel